A weekend warrior. That’s what they called me at the hospital, eight years ago, as I hopped into (oh, irony) the walk-in clinic. The evening before, I’d been playing tennis in Brockwell Park and, my enthusiasm far out-weighing my skill, had hurled myself at a volley with the fervour of a toddler sprinting for an ice cream. The next thing I knew, I was on the ground, my arm flung across my eyes, moaning like a graduate of a Drogba drama class. I actually thought I’d been shot. A bullet in the lower leg. An innocent caught in inter-gang crossfire, taking a slug in a local turf war over the control of Brixton’s sole bowling green.

I hadn’t been shot. What I had done was snap my Achilles tendon, but as I didn’t know, and couldn’t face the chaos of a London A&E on a Friday night, I got a piggyback home and waited until Saturday morning before going for a diagnosis. There, in the walk-in clinic, they told me the bad news. I would need an operation to sew the tendon back together, followed by three months in plaster and then three months learning to walk again. A total of six long months on crutches.

Those months were slow. They passed, but the fear of snapping my Achilles again has never left me. A weekend warrior, I learned then, is someone who was fit once and, in their poor deluded soul, still believes they are. Typically in their late thirties (I was 37), they don’t take regular exercise but chuck themselves around like Space Hoppers on a bouncy castle as soon as the sun comes out. It could be gambolling to the pub, skipping for a Frisbee, a spontaneous in-park football match. And — bam! — your Achilles has gone.

Anyhow, I turned from warrior to worrier. I was OK with no-impact sport — swimming, cycling, yoga — but running for the bus became several steps too far and the very idea of a treadmill gave me The Fear. The Fear of ending up on You’ve Been Framed! wearing my legs as a bow tie, specifically, but also The Fear of my weakened Achilles failing again. And then I had kids, and exercise went out of the window along with after-work cocktails and the concept of the bathroom as a relaxing environment.

Which was… OK, I suppose. I didn’t put on any weight. But as a naturally energetic type (I did a lot of gymnastics as a kid, a lot of raving as an adult), I found that a lack of sport meant an increase in stress. Both my husband and I have jobs with irregular hours, and there’s a lot of mental juggling going on and I just couldn’t calm the chatter in my head. I needed my body to move to stop my mind doing backflips. But clubbing was out, I hate the gym and regular classes were impossible to stick to.

Then, some time last year, I became fixated with running. I kept hearing about people I knew — lazy hacks, floppy fashionistas, insouciant musicians — who had running as part of their lives. Through various connections (Twitter), I discovered Tim Weeks, an ex-Olympic-standard triathlete who specialises in working with women. What I liked about Tim was what I like about most people.

He’s interesting, and interested. And he talks sense. I’ve had two pregnancies and two emergency Caesareans, and he pointed out that this means that my stomach muscles are wrecked and need to be knitted properly back together. He himself had a bad accident that ended his athletic career; he was in hospital for months and told he’d never walk again, let alone run marathons, which he does. My pathetic Achilles injury was like breaking a fingernail to Tim.

Initially, I was concerned that he might be one of those trainers who chuck heavy balls at you in the rain. Nothing of the sort. He just gave me some exercises. Bum twitches, mostly. I had to learn to tense each cheek separately, which gave sitting at the computer a new, interestingly kinky element. Then leg raises and some horrible twisty sit-ups. ‘Do them if you want,’ said Tim. ‘It’s up to you.’ What he was doing was building up my bum and stomach, so that, when I did run, it would be these, rather than my Achilles, that would be doing the work. And he was building up my exercise persona in a realistic way, giving me exercises that would take 15 minutes, rather than an hour. Even I could fit those in.

Our goal became to get me running before Christmas, and in mid-December I bought some trainers. But on the day we were scheduled for my first ever jog round the block, my daughter fell and smashed her nose on the pavement, so I drove to the hospital instead. Still, I definitely raised my heart rate.

My trainers remain unused. They sit, black and neon pink, on the mantelpiece in our bedroom, a trophy as yet un-won. Because I still want to run. I had my kids late and I’d like to be fit enough not to fear a heart attack from playing Operation. I’ve got through most of my life on an excess of nervous energy, and I know that will fade. I need to clear my head from time to time. I want to run. I’m not up for marathons. I just want to run round the park. All the way around Brockwell Park — despite the Achilles incident, my favourite place in London — once. That’s all.

In my heart, despite Tim’s assurances, I don’t truly believe I can do it. But if I keep up those bum twitches, keep gazing at my beautiful trainers, keep pushing aside that weekend-warrior memory then, well, next week I just might.